Scenes III - IV Summary

Scene III: Galileo is with his friend Sagredo at home as both take turns looking through a telescope. Visual evidence points to no other conclusion but that the moon has peaks and valleys just like the earth, which is unheard of. Galileo states that, to an observer on the moon, the earth would appear sometimes like a crescent, sometimes like half a circle, just as the moon does to those on earth.

Priuli visits. Galileo's so-called invention, the telescope, has arrived by the boatload to Venice and will be peddled on every street corner starting in the morning for a mere 2 scudi. The Venetian senators will be furious when they realize their "naval advantage" is something everyone in Europe has. Priuli is hurt and feels swindled by Galileo, who got his money. Galileo states that he may be on to something...